The variation of sunlight throughout the year, caused by the tilt of the Earth’s axis and its spherical shape, influences surface heating, temperatures, atmospheric currents, and rainfall distribution. Solar energy, being clean and sustainable, has many applications. Using it efficiently requires understanding its temporal distribution. The daily accumulation of solar irradiation follows a sigmoidal pattern, which can be described by non-linear regression models. These models offer practical and innovative interpretations for renewable energy projects, filling a gap in the scientific literature. This study was conducted to evaluate the suitability of the Logistic, Gompertz, and Von Bertalanffy non-linear regression models to describe the accumulation of daily global solar irradiation (kJ m-²). Data on global irradiation accumulated throughout the day at ground level, during the equinoxes and solstices in Belo Horizonte/MG, were obtained from the Brazilian National Institute of Meteorology (INMET) through the Annual Historical Data for the period 2018 to 2022. The Logistic and Gompertz models met the evaluated statistical assumptions, unlike the Von Bertalanffy model. The Logistic model achieved a better fit for the equinox and winter solstice data, while the Gompertz model was more suitable for the summer solstice data. The asymptotic estimates (α) of the Logistic model were statistically equivalent for the equinoxes but not for the solstices. The β parameter (abscissa of the inflection point) was statistically equivalent for the solstices and the spring equinox.
Seed dormancy is a constraint in the propagation of forage peanut, limiting large-scale production. Tissue culture techniques, particularly embryo rescue, offer a promising alternative for breaking dormancy and ensuring uniform seedling establishment. This study was developed in order to evaluate the effect of gibberellic acid (GA₃) on embryo germination, with the objective of establishing an efficient protocol for in vitro embryo cultivation. Embryos extracted from four seed lots were cultured on Murashige and Skoog (MS) medium supplemented with five concentrations of GA₃ (0, 10, 20, 40, and 80 mg L-1). Seeds were surface-sterilized with 70% ethanol followed by 2% sodium hypochlorite and rinsed with deionized water. Embryos were excised using a sterile scalpel in a laminar flow hood and cultured as explants for regeneration. After 21 days, germination rate, seedling growth parameters, and photosynthetic pigment contents were assessed. Statistical analyses included analysis of variance (ANOVA) and polynomial regression, with treatment effects compared using Tukey’s test (p ≤ 0.05). A quadratic response was confirmed for most parameters, underscoring the importance of dose optimization. Moderate GA₃ concentrations (40 mg L-1) significantly improved embryo germination compared to the control, whereas higher concentrations (80 mg L-1) negatively impacted chlorophyll content and optimal shoot and root development. GA₃ application during in vitro culture influenced seedling development, promoting shoot elongation and altering pigment composition. In vitro culture proved to be an effective approach for assessing the physiological response of Arachis pintoi seedlings to varying gibberellin levels, contributing to a better understanding of dormancy-breaking mechanisms in this species.
Population dynamics and spatial use by didelphid marsupials are fundamental for understanding gene flow, community structure, and ecosystem functioning, as these animals play key roles in seed dispersal, food web dynamics, metapopulation processes, and disease ecology. However, available data often show contradictory patterns across study areas. This study aimed to describe and analyze the home range of Didelphis albiventris in a broad landscape within the ecotonal region between the Atlantic Forest and Cerrado. Additionally, we examined abundance, sex ratio, reproductive females, residence time or movement between fragments, and their relationships with body mass. Sampling was conducted over 14 months using Tomahawk, Sherman, and pitfall traps in a capture–mark–recapture design. Distances covered ranged from 0.20 to 4.16 km. Home ranges, based on three to six recaptures, varied from 2.10 to 8.49 km in perimeter and 0.0007 to 1.17 km² in area. We captured 146 individuals (95 females and 51 males) with 126 recaptures. The mean litter size was six. The overall sex ratio favored females across all sampled fragments. The average residence time in fragments was 19.33 days. Regression analyses showed no significant relationship between body mass and displacement or permanence. Home ranges were larger than those previously reported. Females were more numerous and exhibited longer and more frequent movements between small forest fragments. Litter size was smaller than that reported for other regions of southeastern Brazil. Overall, D. albiventris in this region showed high abundance, a female-biased population, and expanded spatial use.
Late-season diseases (LSDs) are among the most significant biotic factors limiting soybean yield. Exploring alternative strategies for LSD management yields social, environmental, and economic benefits. This study aimed to evaluate the effectiveness of carboxamide-based fungicide applications in controlling soybean LSDs. The experiment was conducted in Pinhalzinho, São Paulo, Brazil, using a randomized complete block design (RCBD) with five treatments and four replicates, totaling 20 experimental units. Treatments included four fungicide management strategies involving carboxamides and one untreated control. Fungicide applications began 27 days after sowing (DAS) and were repeated every 15 days following disease detection. Evaluated variables included disease severity, area under the disease progress curve (AUDPC), number of pods per plant, number of seeds per pod, grain yield (kg ha⁻¹), and thousand-grain weight. Data were subjected to analysis of variance (ANOVA) and treatment means were compared using Tukey’s test (p < 0.05). Results showed that treatments 2 and 4 were most effective in reducing the progression of target spot and brown spot, respectively. In contrast, treatment 1 exhibited the highest severity of leaf blight. Treatment 2 achieved the highest yield (4974.12 kg ha⁻¹), though yield differences among treatments were not statistically significant. Thousand-grain weight did not differ significantly across treatments, with treatment 3 showing the highest average (185.62 g). Overall, the use of carboxamide-based fungicides contributed to reducing LSD severity and maintaining grain yield, indicating their viability as a tool within integrated disease management strategies.
Sharing agricultural areas with genetically modified corn, conventional corn is subject to drift of glyphosate applied to adjacent areas, requiring evaluation of consequences from this intoxication. Thus, this work was developed in order to evaluate the sensitivity of two conventional corn hybrids to subdoses of glyphosate herbicide. Three similar experiments were conducted in a greenhouse, between November 2023 and May 2024. The first and second experiments assessed the Biomatrix BM3051 conventional hybrid corn; the third experiment evaluated the Semeali XB8018 hybrid corn. All experiments used five subdoses of the glyphosate herbicide, at a highest dose applied of 144 g ha−1. Plants were sprayed at a vegetative stage of three to four leaves. Qualitative (description of anatomical and morphological changes) and quantitative symptoms were evaluated using a visual scale of phytotoxicity and dry matter mass. Glyphosate doses equal to or greater than 36 g ha−1 led to significant intoxication of corn plants, possibly reducing dry matter. Biomatrix BM3051 had greater sensitivity to glyphosate intoxication compared with Semeali XB8018 corn. Most common phytotoxic symptoms observed included (in increasing order of intensity): slight reduction in size, yellowish streaks, wrinkling of the leaf blade, chlorosis or bleaching of young leaves, purplish leaf blade, curled leaves similar to drought damage, excessive formation of adventitious roots, necrosis of older leaves, generalized necrosis, tillering and meristematic damage. For the hybrid Semeali XB8018, glyphosate-induced hormetic effect occurred at doses below 36 g ha−1. Considering 1,440 g ha−1 of glyphosate as a maximum dose, the 36 g ha−1 subdose equals 2.5%. Thus, the severe toxic symptoms observed in the field may result from improper applications rather than from glyphosate drift into adjacent areas.
